Delivery of the correct medication, dose and volume at the appropriate infusion rate and time is essential for safe administration of medication by infusion, generally intravenously.
Drug solutions for administration by infusion are provided in various ways. Certain drug solutions, such as cytostatic drugs, are prepared at hospital pharmacies or at drug manufacturers, whereas other drugs, such as antibiotics and morphine, are prepared at hospital pharmacies or at the wards, either from a base solution or a powder formulation.
While the hospital routines are rigorous, the risk for mistakes by pharmacy and hospital personnel cannot be totally avoided. Not only can mistakes be made in the manual preparation of a drug solution, but for example mix-up of different medicaments may also take place at the moment when the drug container is connected to the device used for the administration. Since drugs for infusion are often highly potent, errors in drug composition and concentration may have serious effects on the patient and can even be fatal.
To eliminate the consequences of such mistakes devices have been proposed which immediately before infusion analysis whether the administration container set up for infusion contains the correct drug or not, and if the concentration of the drug solution is as prescribed.
WO 2004/109262 A1 discloses a method and a device to perform verification of the identity of a drug in an administration container by loading drug from the container to an analyzing unit, non-invasively determining a value of at least one chemical and/or physical property of a drug solution to generate a profile for the drug, and comparing the obtained profile with a set of known profiles. If agreement between the obtained profile and the profile of the prescribed drug is reached a message is issued that the treatment is safe and administration of the drug can proceed. Optionally, also the concentration of the drug is verified before the administration is allowed to proceed. The non-invasive analysis is preferably performed by absorption spectrophotometry.
A similar approach is disclosed in WO 2004/033003 A1, where a device and process for preventing medical errors due to the improper administration of an intravenously delivered medication include spectroscopic analysis of intravenous fluid components. An emission source and a detector are placed adjacent to the intravenous tubing of an administration set to generate signals for spectroscopic analysis. The signals are processed to identify the medication and preferably also the concentration of the medication. In a preferred embodiment, the emission source, detector and hardware and software for the spectroscopic analysis are placed in an infusion pump.
In the devices and processes outlined above, failure to verify the identity of the drug in the drug administration container results in disposal of the container and replacement with a new drug container. Disposal of the drug container would also be the result if the concentration of the drug is determined and is found not to correspond to or to unacceptably deviate from the label concentration.
It is an object of the present invention to provide means for proceeding with the administration of the drug solution even if the determined concentration is not the correct one or is within an acceptable range.
As is well known, drug molecules may adhere to the inner wall of the drug container, such as an infusion bag, which may result in an inhomogeneous drug solution within the container which in turn may result in a varying drug concentration of the drug solution administered to the patient, even if the container has been gently shaken or massaged before the set up. A varying drug concentration may also be due the drug solution undergoing a change during the infusion process.
It is another object of the present invention to deliver a correct dosage of a drug administered by infusion even if the concentration of the administered drug solution varies during the infusion.
It is another object of the present invention to provide a method and a system capable of identifying the drug and the concentration by means of spectrophotometry.